So a group of bad guys and one girl break into a building at night to get something. The main guy was there in that building (no one else was in there) and saw what was going on so he left undetected outside to get a cop. The cop pulls up and the main guy explains to the cop and the cop tries to kill him because he was working with the bad guys. The main guy knocks him out, handcuffs him to a pole or fence or his car and takes his gun. He then decides to kill the bad guys inside one by one. They know theres an intruder because the cop told them before he was handcuffed. So the movie is him trying to stop them. I remember there was 1 girl and she was the girlfriend of the bad boss guy. She gets killed by the main guy or her boyfriend i forgot.
Not a perfect match, but it is a die hard scenario, and there is a corrupt cop in the movie:
“Gridlocked” (2015)?
https://www.imdb.com/title/tt2724532/
When was it made, what do you think? When did you see it?